(1) Field of the Invention
The present invention relates to a process for regenerating ceramic honeycomb filters by removing soot heaped on partition walls thereof through combustion.
(2) Related Art Statement
In ceramic honeycomb filters used in diesel engines or the like, in order to remove soot filtered off from exhaust gases and heaped on partition walls, it is necessary that the soot is removed by combustion after use during a given time period to regenerate the ceramic honeycomb filters.
According to a conventional process for combusting such soot, amounts of a fuel and combustion air are set such that temperatures of waste gases are made sufficiently higher than an ignition temperature of the soot (soot-ignition temperature) so as to enable complete combustion thereof, and these amounts are set at constant values during soot combustion, respectively.
However, in the above regenerating process, since the waste gas having a temperature well higher than the soot-ignition temperature is at one time fed to the ceramic honeycomb filter from the beginning of the soot combustion, soot heaped on the partition walls is rapidly combusted at once. Consequently, there is a problem in that the ceramic honeycomb filter may break or melt.